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Replacing a Data Drive

This page describes how to replace an Unraid array data drive. Why would you want to do that? Any number of reasons...

  • The drive has failed
  • The drive has been acting strange or reporting errors, and you think it might be failing
  • The drive is old or past its warranty period
  • The drive is small or full, and you need more storage space
  • The drive has bad sectors and you want to pull it and replace it so you can Preclear/test/fix it
  • You just bought a new monster of a drive, and want it in the array
  • Any other reason you can think of

Important Notes​

  • If you have purchased a replacement drive, we always recommend Preclearing the replacement drive first, to make sure it's a good drive that won't fail for a few years at least. The Preclearing is not strictly necessary, as replacement drives don't have to be cleared, they are going to be completely overwritten. But Preclearing new drives one to three times provides a thorough test of the drive, eliminates 'infant mortality' failures.

  • It's always good to have a prepared and tested replacement drive already on hand!

  • Important! You cannot replace a drive with one that is LARGER than the parity drive! If your replacement drive is larger than the parity drive, then proceed to The parity swap procedure.

  • Unraid does not require the replacement drive to be the same size as the old drive being replaced. It CANNOT be smaller, but it CAN be a larger drive, up to the size of the parity drive. If too large, Unraid has a special two-step 'Parity Swap' procedure (often called the 'swap-disable') that will use a larger than parity drive to first upgrade the parity drive then replace the old drive with the old parity drive.

  • If you are here because you have a disabled drive, and you have already checked the syslog and SMART report (or got instruction from the Unraid forums), and are SURE that the drive is good, then you can use the procedures below to rebuild it onto itself (below, consider the 'old drive' to be the 'new drive'). There is a similar procedure just for this though → Re-enable the drive.

The procedure​

: If you are running a very old version of Unraid, such as v4.7 or older, skip down to the next section.

  1. Stop the array
  2. Unassign the old drive if still assigned (to unassign, set it to No Device)
  3. Power down
  4. [ Optional ] Pull the old drive (you may want to leave it installed for Preclearing or testing)
  5. Install the new drive
  6. Power on
  7. Assign the new drive in the slot of the old drive
  8. Go to the Main → Array Operation section
  9. Put a check in the Yes, I'm sure checkbox (next to the information indicating the drive will be rebuilt), and click the Start button
  10. The rebuild will begin, with hefty disk activity on all drives, lots of writes on the new drive and lots of reads on all other drives

: All of the contents of the old drive will be copied onto the new drive, making it an exact replacement, except possibly with more capacity than the old drive.

The procedure for Unraid v4​

: This section is only for old versions of Unraid, such as v4.7 or older. If you are running v5 or v6 of Unraid, then go back to the previous section.

  1. Stop the array
  2. Power down
  3. Replace hard drive with new drive.
  4. Turn on
  5. Replaced drive appears with blue dot
  6. Tick the "I'm sure" checkbox, and press "Start will bring the array on-line, start Data-Rebuild, and then expand the file system."
  7. Hefty disk activity and main page will show lots of reading on "the other" disks and writing on new disk as data is being rebuilt.
  8. End